1. Field of the Art
The present invention relates to a method and a device for effecting a spin-testing for a rotor of a turbocharger, and more particularly to such method and device suitable for spinning of the turbocharger rotor with hot gases.
2. Related Art Statement
In the art of motor vehicles, increasing attention is directed at turbocharges which blow an air-and-fuel mixture into the combustion chamber of an engine. Such a turbocharger employs a rotor which is made, for example, from a ceramic material. Since the rotor in use is rotated by exhaust-gas energy of the engine, at a very high speed, e.g., on the order of 100,000 rpm, spin-testing is required to be performed at high speeds at which the rotor is acutally operated. Namely, the rotor is tested in simulated operating conditions, to check the rotor for its operating reliability.
It is desired that a spinning test of the turbocharger rotor be achieved in a simulation testing device in which the turbocharger rotor is rotatably supported in the same conditions as in a turbocharger that is actually incorporated in the motor vehicle. The rotor is spun with a high-velocity stream of gas which is applied to the blade portion of the rotor, while the shaft portion is fixed to a simulation attachment assembly to permit the rotor and the attachment assembly to be rotated as a unit. The simulation attachment assembly corresponds to parts which are acutally connected to the turbocharger rotor. For instance, the spin-testing is performed in the manner which will be described, referring to FIGS. 1(a) and 1(b), and FIGS. 2(a) and 2(b) wherein the turbocharger rotor is indicated generally by 1.
Initially, the turbocharger rotor 1 consisting of a blade portion 1a and a shaft portion 1b is dynamically balanced without the simulation attachment assembly attached. Subsequently, a thrust bearing 2, a spacer 3, a compressor rotor or sleeve 4, and a lock nut 5, which constitute the simulation attachment assembly, are mounted on the shaft portion 1b of the rotor 1, in the order of description. Then, the integral turbocharger rotor and attachment assembly are dynamically balanced as a unit.
Subsequently, the attachment assembly is separated from the turbocharger rotor 1, and the rotor 1 is set in place in a testing device which includes a bearing support 9, a bearing housing 10, a turbine housing 11, and the attachment assembly 2-5. The rotor 1 is installed such that its shaft portion 1b extends through the bearing housing 10 while its blade portion 1a is located within a gas passage 11a formed in the turbine housing 11. The thrust bearing 2, bearing support 9, spacer 3, and compressor rotor or sleeve 4 are fitted on the shaft portion 1b, and are fixed thereto with the lock nut 5. In this connection, it is noted that the component parts 2-5 of the simulation attachment assembly should be attached to the shaft portion 1b of the rotor 1, with the same angular phases relative to the shaft portion 1b, as established when the unit of the rotor 1 and the assembly 2-5 was dynamically balanced.
The bearing housing 10 has an oil passage 13 which is connected at its inlet 15 to a lubricant hose 18 via a flange 14 attached adjacent to the inlet 15. A lubricant from the lubricant hose 18 is introduced through the inlet 15 so as to flow through the passage 13 and to be discharged through an outlet 17. The testing device is provided with a vibration meter 16 (vibrometer) of an acceleration type, which is mounted on the flange 14. The vibration meter 16 senses vibrations of the testing device during a spin-testing of the turbocharger rotor 1 with the attachment assembly 2-5. In FIGS. 2(a) and 2(b), reference numerals 6, 7, 8 and 19 indicate a sealing ring, a snap ring, a radial bearing, and a mechanical seal, respectively.
Problem Solved by the Invention
As described above, the spin-testing method to be practiced on the testing device indicated above requires a procedure of dynamically balancing the rotor 1 and the simulation attachment assembly 2-5 fixed to the shaft portion 1b, before the rotor 1 is set in place on the testing device. Further, after the dynamic balancing of the integral rotor 1 and the attachment assembly 2-5, the component parts of the attachment assembly, that is, the thrust bearing 2, spacer 3, compressor rotor or sleeve 4 and lock nut 5 should be attached to the shaft portion 1b of the rotor 1 so that the individual component parts 2-5 have the same angular phases or positions with respect to the turbocharger rotor 1. Therefore, the testing method requires a cumbersome time-consuming procedure for accurate alignment of the components parts 2-5 with the rotor 1. Furthermore, the bearing support 9 must be removed when the rotor 1 is installed on and removed from the testing device. Consequently, the fluid-tight sealing between the bearing housing 10 and the bearing support 9 must be re-established. Thus, the installation and removal of the turbocharger rotor 1 requires a lot of time as much as one hour for example, and a relatively high level of skill. While the above-indicated known method is satisfactory where the number of the rotors 1 is comparatively small, such method is not considered sufficiently effective when it is required to accomplish the spin-testing of a large number of rotors within a relatively short period of time.